Double-blind crossover study of once daily nifedipine coat core in essential hypertension.

Nineteen patients with essential hypertension on regular treatment with nifedipine tablets 20 mg twice daily and whose DBP was < 95 mmHg on at least two occasions two weeks apart were entered in a double-blind randomised crossover study of three weeks treatment with nifedipine coat core (new formulation) either as 30 mg one daily or as 60 mg once daily dose. BP and plasma nifedipine levels were measured at 24, two, four and six hours after dosing. The pattern of BP response to both doses was similar over the 24h period. However, a greater BP lowering effect was achieved with 60 mg compared with 30 mg. The BP lowering effect of both doses was less at 24h after the last dose compared with peak effect. Plasma nifedipine levels were significantly associated with the BP lowering effect in the group as a whole (i.e. the higher the nifedipine levels, the lower the BP) and were significantly less at 24 hours compared with peak. Nifedipine in the coat core formulation is effective in lowering BP in patients with essential hypertension. The 60 mg dose is more effective than the 30 mg dose and induces higher nifedipine levels which are associated with greater BP lowering effect. However, the maximum BP lowering effect is not maintained up to 24 hours.